Japanese Patent Application Laid-Open Publication No. 2013-115336 (Patent Document 1) discloses that bonding strength of a bump is improved by providing a protruding portion 1j, which protrudes in a horizontal direction, in a columnar electrode 1i to which the bump is bonded.
Japanese Patent Application Laid-Open Publication No. 2006-59917 (Patent Document 2) discloses a technique of providing a core bump 5 having locking means formed on an element electrode 3 and an external circuit connection bump 2 with which the core bump 5 is coated, thereby securing a bump height after the secondary mounting and achieving the stress relaxation.
Japanese Patent Application Laid-Open Publication No. 2001-53200 (Patent Document 3) discloses a technique of providing a first sealing resin film 8 which coats and surrounds a solder bump 7 formed above an electrode pad 3 with a metal multilayer film 6 interposed therebetween and a second sealing resin film 9 which coats a rear surface side of a semiconductor substrate 2, thereby achieving the thickness reduction while maintaining the strength.
FIG. 1 of Japanese Patent No. 3089943 (Patent Document 4) discloses a solder bump electrode 18 in which a Cu electrode 16 having a mushroom shape is formed on a metal wiring 12 with a barrier layer 14 or the like interposed therebetween and a solder layer 17 is further formed thereon.